1 /*
2 * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /*
29 * @OSF_COPYRIGHT@
30 */
31 /*
32 * Mach Operating System
33 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
34 * All Rights Reserved.
35 *
36 * Permission to use, copy, modify and distribute this software and its
37 * documentation is hereby granted, provided that both the copyright
38 * notice and this permission notice appear in all copies of the
39 * software, derivative works or modified versions, and any portions
40 * thereof, and that both notices appear in supporting documentation.
41 *
42 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
43 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
44 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
45 *
46 * Carnegie Mellon requests users of this software to return to
47 *
48 * Software Distribution Coordinator or [email protected]
49 * School of Computer Science
50 * Carnegie Mellon University
51 * Pittsburgh PA 15213-3890
52 *
53 * any improvements or extensions that they make and grant Carnegie Mellon
54 * the rights to redistribute these changes.
55 */
56 /*
57 */
58
59 #ifndef _KERN_TIMER_H_
60 #define _KERN_TIMER_H_
61
62 #include <kern/kern_types.h>
63
64 /*
65 * Some platforms have very expensive timebase routines. An optimization
66 * is to avoid switching timers on kernel exit/entry, which results in all
67 * time billed to the system timer. However, when exposed to userspace,
68 * we report as user time to indicate that work was done on behalf of
69 * userspace.
70 *
71 * Although this policy is implemented as a global variable, we snapshot it
72 * at key points in the thread structure (when the thread is locked and
73 * executing in the kernel) to avoid imbalances.
74 */
75 extern int precise_user_kernel_time;
76
77 /*
78 * thread must be locked, or be the current executing thread, so that
79 * it doesn't transition from user to kernel while updating the
80 * thread-local value (or in kernel debugger context). In the future,
81 * we make take into account task-level or thread-level policy.
82 */
83 #define use_precise_user_kernel_time(thread) (precise_user_kernel_time)
84
85 /*
86 * Definitions for high resolution timers.
87 */
88
89 #if __LP64__
90 #define TIMER_ALIGNMENT
91 #else
92 #define TIMER_ALIGNMENT __attribute__((packed, aligned(4)))
93 #endif
94
95 struct timer {
96 uint64_t tstamp;
97 #if defined(__LP64__)
98 uint64_t all_bits;
99 #else /* defined(__LP64__) */
100 /* A check word on the high portion allows atomic updates. */
101 uint32_t low_bits;
102 uint32_t high_bits;
103 uint32_t high_bits_check;
104 #endif /* !defined(__LP64__) */
105 } TIMER_ALIGNMENT;
106
107 typedef struct timer timer_data_t, *timer_t;
108
109 /*
110 * Initialize the `timer`.
111 */
112 void timer_init(timer_t timer);
113
114 /*
115 * Start the `timer` at time `tstamp`.
116 */
117 void timer_start(timer_t timer, uint64_t tstamp);
118
119 /*
120 * Stop the `timer` and update it with time `tstamp`.
121 */
122 void timer_stop(timer_t timer, uint64_t tstamp);
123
124 /*
125 * Update the `timer` at time `tstamp`, leaving it running.
126 */
127 void timer_update(timer_t timer, uint64_t tstamp);
128
129 /*
130 * Update the `timer` with time `tstamp` and start `new_timer`.
131 */
132 void timer_switch(timer_t timer, uint64_t tstamp, timer_t new_timer);
133
134 /*
135 * Update the thread timer at an "event," like a context switch, at time
136 * `tstamp`. This stops the current timer and starts the `new_timer` running.
137 *
138 * Must be called with interrupts disabled.
139 */
140 void processor_timer_switch_thread(uint64_t tstamp, timer_t new_timer);
141
142 /*
143 * Return the difference between the `timer` and a previous value pointed to by
144 * `prev_in_cur_out`. Store the current value of the timer to
145 * `prev_in_cur_out`.
146 */
147 uint64_t timer_delta(timer_t timer, uint64_t *prev_in_cur_out);
148
149 /*
150 * Read the accumulated time of `timer`.
151 */
152 #if defined(__LP64__)
153 static inline
154 uint64_t
timer_grab(timer_t timer)155 timer_grab(timer_t timer)
156 {
157 return timer->all_bits;
158 }
159 #else /* defined(__LP64__) */
160 uint64_t timer_grab(timer_t timer);
161 #endif /* !defined(__LP64__) */
162
163 #endif /* _KERN_TIMER_H_ */
164